工程科学学报
工程科學學報
공정과학학보
Journal of University of Science and Technology Beijing
2015年
11期
1477-1484
,共8页
自旋梯状化合物%固相反应%电输运性质%磁学性质%磁化率%电阻率
自鏇梯狀化閤物%固相反應%電輸運性質%磁學性質%磁化率%電阻率
자선제상화합물%고상반응%전수운성질%자학성질%자화솔%전조솔
spin ladder compounds%solid-state reactions%electronic transport properties%magnetic properties%magnetic suscep-tibility%electrical resistivity
采用标准固相反应法制备了Sr14(Cu1-xZnx)24O41(x=0, 0. 01, 0. 02, 0. 03)系列多晶样品. X射线衍射谱表明所有样品均呈单相,且样品晶格常数大小随Zn掺杂量x的变化存在微弱波动. X射线光电子能谱表明Sr14Cu24O41中Cu离子以+2价形式存在,Zn掺杂对体系中Cu离子化合价不造成影响. 磁化率测量结果表明在10~300 K温度范围内Zn掺杂使体系磁化率降低,拟合结果表明随着Zn掺杂量x的增大,居里-外斯项对体系磁化率贡献逐渐减弱,二聚体耦合能JD 逐渐降低,每个分子中CuO2 自旋链内二聚体个数ND 与自由Cu2+离子自旋数NF 均逐渐减少,进一步分析显示替换二聚体内Cu2+离子的Zn2+离子数少于替换自由Cu2+离子的Zn2+离子数. 电阻率测量结果表明Sr14Cu24O41体系具有半导体特性,并且Zn掺杂会使体系电阻率降低,降低程度随掺杂量x增大而增大,但并未使体系发生金属- 绝缘体转变. 认为电阻率降低可能是由于Zn2+离子掺杂使体系内CuO2 自旋链中二聚体发生退耦,破坏了电荷有序超结构,从而使更多的空穴释放出来并转移到导电性好的Cu2O3自旋梯子中所致.
採用標準固相反應法製備瞭Sr14(Cu1-xZnx)24O41(x=0, 0. 01, 0. 02, 0. 03)繫列多晶樣品. X射線衍射譜錶明所有樣品均呈單相,且樣品晶格常數大小隨Zn摻雜量x的變化存在微弱波動. X射線光電子能譜錶明Sr14Cu24O41中Cu離子以+2價形式存在,Zn摻雜對體繫中Cu離子化閤價不造成影響. 磁化率測量結果錶明在10~300 K溫度範圍內Zn摻雜使體繫磁化率降低,擬閤結果錶明隨著Zn摻雜量x的增大,居裏-外斯項對體繫磁化率貢獻逐漸減弱,二聚體耦閤能JD 逐漸降低,每箇分子中CuO2 自鏇鏈內二聚體箇數ND 與自由Cu2+離子自鏇數NF 均逐漸減少,進一步分析顯示替換二聚體內Cu2+離子的Zn2+離子數少于替換自由Cu2+離子的Zn2+離子數. 電阻率測量結果錶明Sr14Cu24O41體繫具有半導體特性,併且Zn摻雜會使體繫電阻率降低,降低程度隨摻雜量x增大而增大,但併未使體繫髮生金屬- 絕緣體轉變. 認為電阻率降低可能是由于Zn2+離子摻雜使體繫內CuO2 自鏇鏈中二聚體髮生退耦,破壞瞭電荷有序超結構,從而使更多的空穴釋放齣來併轉移到導電性好的Cu2O3自鏇梯子中所緻.
채용표준고상반응법제비료Sr14(Cu1-xZnx)24O41(x=0, 0. 01, 0. 02, 0. 03)계렬다정양품. X사선연사보표명소유양품균정단상,차양품정격상수대소수Zn참잡량x적변화존재미약파동. X사선광전자능보표명Sr14Cu24O41중Cu리자이+2개형식존재,Zn참잡대체계중Cu리자화합개불조성영향. 자화솔측량결과표명재10~300 K온도범위내Zn참잡사체계자화솔강저,의합결과표명수착Zn참잡량x적증대,거리-외사항대체계자화솔공헌축점감약,이취체우합능JD 축점강저,매개분자중CuO2 자선련내이취체개수ND 여자유Cu2+리자자선수NF 균축점감소,진일보분석현시체환이취체내Cu2+리자적Zn2+리자수소우체환자유Cu2+리자적Zn2+리자수. 전조솔측량결과표명Sr14Cu24O41체계구유반도체특성,병차Zn참잡회사체계전조솔강저,강저정도수참잡량x증대이증대,단병미사체계발생금속- 절연체전변. 인위전조솔강저가능시유우Zn2+리자참잡사체계내CuO2 자선련중이취체발생퇴우,파배료전하유서초결구,종이사경다적공혈석방출래병전이도도전성호적Cu2O3자선제자중소치.
A series polycrystalline samples of Sr14(Cu1-xZnx)24O41(x=0, 0. 01, 0. 02, 0. 03) were prepared by standard solid-state reactions. X-ray diffraction ( XRD) patterns show that a single phase can be achieved in all samples and their lattice parameters have weak fluctuation with the change of doping content x. X-ray photo-electron spectroscopy results show that the valence of copper ions in Sr14Cu24O41 is +2 and Zn doping has no effect on the valence of copper ions. Magnetic susceptibility measurements in a temperature range from 10 to 300 K show that Zn doping decreases the magnetic susceptibility of the Sr14Cu24O41 system. Experimental fitting results show that the contribution to magnetic susceptibility of the Curie-Weiss term, the value of coupling energy in dimers JD , the number of dimers ND and the number of free Cu2+ ion spins in the CuO2 spin chain per formula unit NF all decrease with the increase of doping content x. Further analysis indicates that the number of Zn2+ ions which substitute Cu2+ ions in dimers is less than the number of Zn2+ ions which substitute free Cu2+ ions. Electrical resistivity measurements show that the Sr14 Cu24O41 system is semiconducting, Zn doping decreases the electrical resistivity of the Sr14Cu24O41 system, and the decreasing level increases with the increase of doping content x, but no metal-insulator transition occurs in this system. We think that the decrease in electrical resistivity maybe results from decoupling of dimers in the spin chain due to Zn2+ ion doping. It means that the charge order super structure is destroyed, so more holes are released and transferred into the spin ladder then participate in conducting.
